Respiratory apparatus



Aug. 13, 1963 R. G. BARTLETT, JR

RESPIRATORY APPARATUS Filed March 7, 1961 3 Sheets-Sheet l FJQJ.

FRDH OXYGEN SUPPLY JNVENTOR. F0 5:05 G. BMWZETT JR.

BY E

ATTORNE 7 1963 R. G. BARTLETT, JR 3,100,485

RESPIRATORY APPARATUS Filed March 7, 1861 3 Sheets-Sheet 2 a: 52 53 a 6MW 644- 46 42' y j k WATV/JV/AW/TV/FV/A/TF/TVW/ INVENTOR.

ATTORNEY I 36 Roscoe G. BARTLETT J Aug 13, 1963 R. s. BARTLETT, JR3,190,485

RESPIRATORY APPARATUS Filed March 7, 1961 3 Sheets-Sheet 3 3 9 INVENTORRoscoe G. BARTLETTJR.

.2; a BY ATTORNEY United States Patent 3,190,485 RESPIRATORY APPARATUSRoscoe G. Bartlett, .lr., Liliian, Ala. Filed Mar. 7, 1961, Ser. No.94,691 5 Claims. (Cl. 128-142) (Granted under Title 35, US. @0113(1952), see. 266) The invention described herein may be manufactured andused by or for the Government of the United States of America forgovernmental purposes without the payment of any royalties thereon ortherefor.

This invention relates generally to respiratory apparatus andparticularly to an improved respiratory apparatus providing adequatemoisture transfer, self-regulating breathing stimulus, and economicaluse of supplied pressurized oxygen.

To prevent the freezing of valves, gauges, and other gear associatedwith the storage of oxygen, both the liquid and compressed forms of thisgas are supplied to theuser in as dry a form as possible, i.e., allwater or water vapor has been extracted. Although breathing of dryoxygen for a short time is without serious effects, prolonged breathingresults in drying of the mucous membranes of the respiratory tract withaccompanying discomfort, sore throat, and head colds. Where, at highaltitudes or other perhaps clinical reasons, pure oxygen without airdilution must be supplied to a user, some means of humidifying theoxygen breathed by the user must be supplied. Such humidification couldbe accomplished by bubbling the oxygen through water, passing it througha water spray, or passing it through or over water containing material.Such means have the principal disadvantage that the moisture must besupplied from an external source which, with the necessary apparatus,increases the weight of the device and limits the duration of its use.

Another approach to the problem concerns the recycling of water from themoist expired breath to the dry incoming oxygen. This method has severalmerits. First, the device would be self-perpetuating in operation andobviously would be much lighter than if water were continuously suppliedfrom an outside source. Second, in a small confined space, such as acockpit or space capsule, this method of recycling would be advantageousin maintaining low humidity of the atmosphere therein, thus preventingmany of the problems associated with thecondensation of water on theinstruments or viewing ports.

The undesirable effects of hyperventilation leading to an abnormal lossof carbon dioxide from the blood are well known. On an average, thehuman body maintains a constant volume of carbon dioxide in the lungs,approximately 5.6%. This CO is necessary for the health and well beingof the body. A rise in the percentage of CO increases the rate ofbreathing; an increase of 0.2% generally doubles the rate of breathing.A fall in the per centage decreases the rate of breathing with danger ofcessation and dangerously upsets the acid-alkaline balance of the humanphysiological system leading to alkalosis.

Hyperventilation may be caused by various physiological, psychologicaland physical factors. One of these fac tors is that the respiratorypassages ofler little resistance to the movement of the rarefiedatmosphere at high altitudes. This condition leads to the userssensation of an inade quate alveolar ventilation. The use of the mask,itself, pro- 3,10%,435 Patented Aug. 13, 1963 duces a sensation ofsuffocation that induces a tendency toward induced rapid and deepbreathing. The use of respiratory apparatus presents diflerent pressuresto the respiratory tracts and lungs which, again, leads tohyperventilation, even in the experienced.

In using oxygen from a compressed source in a respiratory apparatus, itis obvious that some oxygen will be lost to the surrounding atmosphere.As the supply of oxygen is naturally and necessarily limited, due toweight and space limitations, every effort must be made to conserve thisfluid and prevent its loss.

The principal object of my invention, therefore, is to provide arespiratory apparatus, particularly for aviators flying at highaltitudes, including space flight, which will eiilciently incorporatethe foregoing features of moisture transfer from expired to inspiredbreath; the alleviation and prevention of hyperventilation; and plannedeconomy in the use of-the limited supply of additive respirant fluid.

Another object of myinvention is to provide a respiratory apparatuswherein the mask used to couple the apparatus to the respiratory tractsmay be extremely simple, valveless, light of weight and offer noobstructions to voice communications when a proper microphone is bornethereby.

A further object of my invention, contrary to the standard practiceheretofore employed, is to provide an added anatomical dead space to andin the respiratory apparatus for promoting better and more effectivebreathing by the user.

A still further object of my invention is to provide respiratoryapparatus wherein the functions of moisture transfer and increased,improved ventilation are selfpriming and self-perpetuating in that noexternal sources of moisture or other external arrangements forpromoting breathing are necessary.

Other objects and advantages of my invention will appear in connectionwith the following detailed description and the accompanying drawingswherein:

FIGURE 1 is a partly sectioned perspective view of my improvedrespiratory apparatus;

FIG. 2 is a partly sectioned plan view of the principal respiratorymember;

FIG. 3 is a sectional side elevation of the respiratory member taken onthe line 3-3 of FIG. 2;

FIG. 4 is a partly sectioned end elevation of the respiratory membertaken on the line 4-4 of FIG. 3;

FIG. 5 is a partly sectioned end elevation of the respiratory membertaken on the line 5-5 of FIG. 3; and

FIGS. 6-11, inclusive, are diagrammatic views illustrating theprinciples of operation of my improved respiratory apparatus.

With reference to FIG. 1, my improved respiratory apparatus comprises avalveless mask 20, a flexible tube 21, a

respirant supply flexible tube 22, and the principal respirar 3 presenceof valves in the mask near the microphone not only present a noiseproblem due to the operation of the valves but the latter also serve todistort the sound waves between the larynx and the microphone.

The tube 21 between the mask and the respiratory memher 31 is providedfor the important function of designedly increasing the anatomical deadspace between the lungs and the necessary expiratory and inspiratoryvalves.

Heretofore, it has been considered mandatory to keep the connectionsbetween the mask and the source of added respiratory fluid as short aspossible. Such limitation has been imposed apparently because of thefancied overstressed difficulties in breathing at high altitudes andalso possibly because the designers envisaged the use of open cockpitssubject to the extreme low temperatures there encountered. In the latterprior art, showing the addition of a rebreather bag between the valvedmask and the oxygen source, it is universally asserted that the volumeof the rebreather bag must always be less than the normal volume of aircontained in the expanded lungs of the average user. This requirementwas based on the assumption that some provision had to be made to expelas much of the expired CO as possible. Actually, it has been found that,at high altitudes and under conditions requiring the breathing ofpractically 100% oxygen for prolong-ed periods, such arrangementseliminated too much from the respiratory system and resulted in thephysiological effects previously mentioned with reference to thelowering of the CO content of the lungs. Consequently, tube 21, having avolume of approximately 250 cc. in the prototype has been added tocorrect this deficiency. The actual use of this added anatomical deadspace and its important functions will be more fully described later.

Tube 22 is supplied to furnish the necessary connection between therespiratory member and the source of pressurized respirant (not shown).

Respiratory member 30, as shown in FIGS. 2-5, inclusive, consists of ahollow box-like structure 32 having a top lid portion 34; a bottomportion 40; end pieces 50, 51; an expiratory valve 60; an inspiratoryvalve 70; a flexible bellows or diaphragm S0; and a wicking or moisturetransfer membrane 85.

Top lid portion 34 may be hollowed out or may be constructed, as shown,from five rectangular pieces of material, i.e., top plate 35, sidepieces 36 and end pieces 37. T hese' pieces may be rabbeted, as shown,and are hermetically-sealed to each other by adhesive or cement reinforced by the screws 38. An aperture 61 is provided in top plate forcommunication with the expiratory valve 60. Upper ports 39 are providedin the end pieces 37 for the passage of breathing fluids as will be morefully explained later.

The bottom portion 40 is constructed to match the lid portion 34 and mayconsist of sides 41, end pieces 42, 43, and a perforated bottom'plate44. As in the lid portion,

the side and end pieces may be rabbete-d and adhesively securedtogether, further reinforced by the screws 45. Lower ports 46 may beformed in the left hand end piece '42 for purposes to be hereinafterdescribed. Bottom plate 44 is provided with a plurality of apertures 47for leading atmospheric air into the bottom portion.

The flexible impervious diaphragm or bellows 80 is enclosed in thebottom portion 40 and is secured hermetically between the sides 41, endpieces 42, 43, and the lower bottom plate 44. This bellows is of a sizesuflicient to substantially fill the entire bottom portion 4t) whendistended.

The wicking or moisture transfer membrane 85 is stretched andhermetically sealed between the upper and bottom portions of therespiratory member 30. This wicking may be of any suitable material withthe important limitation, however, that its structure must producetransverse channels for the capillary action required in transferringmoisture from the lower portion to the upper portion of the respiratorymember. 0f the many materials 4. tested, a commercial'disposable handtowel, made of rag and wood fibers laid down by a felting process, wasfound to give the best performance. Other materials could, of course, bespecially designed and constructed for this purpose.

Top plate 35 supports the vertically extending expiratory valve 6i). Asshown in 'FIG. 3, this valve may be of more or less standardconstruction and consists principally of a spring loaded valve plate 62pressed against its seat 63. By varying the loading of the spring 64,this valve may be set to allow discharge of the expired breath at adesired pressure relationship. Aperture 61, of course, provides theegress from the chambers in the respiratory member 30 to and through thevalve 60.

. The inspiratory valve 7%, as shown in-FIGS. 2 and 3, which issupported by end piece 51, may also be of standard construction.Itconsists principally of a supporting case 71 which may be screwed intoa threaded hole in the end piece. This casing bears the tube 22connector 72 with its usual sealing rings 73. A thin perforateddiaphragm 77 is supported in the other end of the casing. A flexiblerubber diaphragm 74 is supported inwardly of the other diaphragm by thespider 75 and the spindle 76. When inspiring, the partial vacuum createdin the respiratory member 30 with the pressure of the incoming respirantforces the rubber diaphragm to open to the left or inwardly, asindicated in phantom in FIG. 2.

The end piece 50, FIGS. 2 and 3, is formed with an integral connector 52for connection to the tube 21. This end piece 50 is provided with aninternal, rectangular cavity 5 3 which connects the bore of connector 52with the four ports adjacent thereto.

As previously noted, end piece 42 of the bottom portion 40 is formedwith two oblong ports 46 which are the same size as ports 39 formed inthe top portion end piece 37. Thus, at the mask end of the respiratorymember 30' there are four ports, two above the wicking and two below. Atthe pressurized gas end, there are only two ports and these are situatedabove the wicking. With this porting arrangement expiratory fluid canpass both below and above the wicking while the inspired suppliedrespirant must pass above the wicking.

The principles of the operation of my invention will now be described inconnection with FIGS. 6-11, inclusive.

FIGS. 6 and 7 illustrate diagrammatically the recycling of the moisturefrom the expired to the inspired breath.

During the first part of the expiration, FIG. 6, the lower chamber ofthe respiratory member is filled with moist warm air; the bellows ordiaphragm .80 collapses on the perforated bottom plate 44. As this aircools, the moisture condenses out on the walls of the chamber and theupper surface of the bellows. As the expiration continues, the expiredair passes into and through the upper chamber over the wicking and thenthe remainder passes outwardly through the expiratory valve 60. Duringthis latter period, as the velocity of the expired air is diminished,condensation of moisture is occurring also throughout the length of theadded anatomical dead space represented by the tube 21.

During the first part of the inspiration, as shown in FIG. 7, thenegative pressure or suction produced empties the lower chamber of therespiratory member 30 before the inspiratory valve opens to admit theoxygen or other respirant from either a liquid or compressed fluidsource. The air or fluid trapped in this lower chamber is, of course,humidified. When the bellows or diaphragm is forced against the wickingmaterial, all of the condensed moisture is transferred to and throughthe wicking or moisture transfer membrane. The first part of theinspired breath, then, should be 100% moisture saturated. The secondpart of the inspiration is respirant which has been drawn over the uppersurface of the wicking where it is partly humidified. As the partiallyhumidified respirant is drawn along the added dead space tubing, itpicks upfurther moisture from that condensed on these surfaces until, asthe respirant reaches the mucous membranes and lungs of the user, it hasbeen substantially humidified. Because of the temperature differencebetween the ambient atmosphere and thebody of the user, it should bestressed that only 50% of themoisture from the expired breath need betrapped to saturate completely the inspired breath. It should also benoted here that excess moisture is eliminated during expiration throughthe expiratory valve and as the remaining moisture trapped in the addeddead space and the respiratory member and on the wicking is utilizedcompletely in humidifying the inspired breath, including the 100% dryrespirant, no moisture can collect as an unused liquid. This collectionof unused moisture, which gradually filled the receptacles provided, wasthe fatal defect in all the rebreather types of apparatus found in theprior art.

FIGS. 8 to 11, inclusive, illustrate the functions and provisions of myinvention in preventing hyperventilation, promoting better breathing,and saving respirant. These provisions consist of the added anatomicaldead space provided by the tubing 21 and the respiratory member 30 whichare used in the prevention of hyperventilation and the lower collapsiblechamber of the respiratory member which traps the unused oxygen orrespirant and makes it available as the first portion of the inspiredbreath.

FIG. 8 shows the beginning of expiration. The air in the upper portionof the lungs 86, the anatomical dead space 87, and the added anatomicaldead space 21 is rich in unused oxygen or other provided respirant. Thisis first expelled and is collected and trapped in the lower chamber ofthe respiratory member 30 by collapsing the bellows or diaphragm 85against the perforated lower or bottom plate 44. As the expirationcontinues, FIG. 9, and the lower chamber is completely filled, thelatter portion of this air passes across the top of the wicking 85 andout through the expiratory valve 60. This latter portion is, of course,less rich in' oxygen. During the last stage of expiration, the alveolarair 88, which is rich in CO is expelled from the lungs into theanatomical and added anatomical dead spaces. The shaded portion 89, FIG.9, indicates that portion of the air remaining in the anatomical deadspace which is richest in CO As inspiration commences, FIG. 10, theexpiratory valve 60 closes and the first part of the breath drawn intothe lungs is the CO rich portion 89 which was present in the anatomicaldead space and part of the added anatomical dead space tube 21. This COrich mixture increases somewhat the rate and depth of respiration, asdesigned, and effectively prevents hyperventilation and its accompanyingsymptons of light-headedness, dizziness and disorientation. This portionis then followed by the O rich portion which was trapped in the lowerchamber of the respiratory member due to the ambient pressures forcingthe bellows 8t) upwardly against the wicking 85. Upon the exhaustion ofthe O rich gas from the lower chamber, FIG. 11, the inspiratory valve 70opens and fresh oxygen or other respirant 91 enters the upper chamberover the wicking 85 and on into the succeeding passages and the upperpart of the lungs.

As has thus been explained, the purpose of the added anatomical deadspace is two-fold: (1) to provide a selfregulating stimulus forincreasing the rate and depth of breathing; and (2) to provide aself-limiting reservoir of CO .for the prevention or reduction ofhyperventilation. Although breathing tubing 21 has been used to producethese eifects, the added dead space could also be provided by a box orchannel or space within an airtight helmet. The use of a breathing tube,however, permits the placing of the other components of the device atsome convenient distance from the users mask.

While dimensions and materials are of no critical importance in theconstruction and operation of my invention, tubing 21 could containapproximately 250 cc. of fluid while the respiratory member 30 mayoccupy approximately 45 cu. in. of space. The tubing 21 may be ofstandard materials, textile or rubber. The respiratory .member 30 may beconstructed of plastic or thin light metals. While the latter might bemore advantageous insofar as maximum condensation is concerned,provision must be made for the hermetic sealing required. The materialsof the bellows and wicking have been mentioned previously.

Having thus described a preferred embodiment of my invention,I do notintend, however, to be limited thereby. Such modifications as maysuggest themselves to those skilled in the art will undoubtedly fallwithin the spirit of the invention and the scope of the appended claimswherein I claim:

l. A respiratory apparatus for users of pressurized respirantcomprising:

a valveless mask adapted to hermetically cover the mouth and nose of auser;

a first flexible tubular connection leading outwardly from said mask,said first connection constituting an added anatomical dead space and amoisture collector from the expired breath of said user;

a source of dry pressurized respirant;

a second flexible tubular connection leading from said source of drypressurized respirant;

a respiratory member interposed between said first and secondconnections and connected thereto, said res-' moisture therefrom, and asecond chamber open to both first and second connections, said secondchamber having an expiratory check valve leading to ambient atmosphereand an inspiratory check valve between said second chamber and saidsecond connection to said source of respirant, said second chamberconstituting a channel for conducting a portion of said expired breathto atmosphere and for conducting said dry pressurized respirant to saidfirst connection incident to the controlled opening of said valves, andsaid respiratory member having a moistune transfer membrane separatingsaid first and second chambers whereby the miosture collected in saidfirst chamber is transferred to the dry respirant passing through saidsecond chamber. 2. A respiratory apparatus as defined in claim 1 whereinsaid first chamber of said respiratory member has a main innerhorizontal wallconsisting of said moisture transfer membrane and a mainouter horizontal wall consisting of a flexible diaphragm, said flexiblediaphragm being capable of closely lining the other walls of said firstchamber, including contacting the entire undersurface of said membrane.

3. A respiratory apparatus as claimed in claim 1 wherein saidrespiratory member is a box-like structure comprising:

a shallow lid portion having side and end walls depending from ahorizontal top plate;

an opening through said top plate;

said expiratory check valve mounted 'on the outer surface of said topplate over said opening;

a plurality of ports in each end wall, said ports leading to said firstand second connections;

a bottom portion having side and end walls extending upwardly to meetthe walls of said lid portion;

a perforated bottom plate in said bottom portion secured to said end andside walls;

a flexible diaphragm hermetically secured between said bottom portionend and side walls and said perforated bottom plate;

a plurality of ports in one end wall of said bottom portion, said portsleading to said first connection;

a moisture transfer membrane hermetically secured between the respectiveend and side walls of said lip and bottom portions; and

said inspiratory check valve interposed between the I? Y r plurality ofports in one of the end walls of said her, including the inner surfaceof the diaphragm, to the lid portion and said second connection.underside of said moisture transfer membrane;

4. A respiratory apparatus as claimed in claim 2 Wherein said firstchamber of said respiratory apparatus has an additional perforated rigidouter yvall disposed in juXta- References Cited m the file of thlsPatent position to said flexible diaphragm whereby the interior V UNITEDSTATES PATENTS surface of said diaphragm is subject to the pressures of2,387,123 Deming Oct 16 1945 the expired breath trapped therein and itsexterior sur- 2,610,038 Phillips Sept 9 1952 face is subject to ambientatmosphere pressures. 3,005,453 wenenstein et a1 Oct 24, 1961 -5. Arespiratory apparatus as claimed in claim 2 where- 10 in said flexiblediaphragm constitutes the means to trans- FOREIGN PATENTS fer themoisture collected on the walls ofssaid first cham- 1,121,482 FranceApr. 30 1956

1. A RESPIRATORY APPARATUS FOR USERS OF PRESURIZED RESPIRANT COMPRISING:A VALVELESS MASK ADAPTED TO HERMETICALLY COVER THE MOUTH AND NOSE OF AUSER; A FIRST FLEXIBLE TUBULAR CONNECTION LEADING OUTWARDLY FROM SAIDMASK, SAID FIRST CONNECTION CONSTITUTING AN ADDED ANATOMICAL DEAD SPACEAND A MOISTURE COLLECTOR FROM THE EXPIRED BREATH OF SAID USER; A SOURCEOF DRY PRESSURIZED RESPIRANT; A SECOND FLEXIBLE TUBULAR CONNECTIONLEADING FROM SAID SOURCE OF DRY PRESSURIZED RESPIRANT; A RESPIRATORYMEMBER INTERPOSED BETWEEN SAID FIRST AND SECOND CONNECTIONS ANDCONNECTED THERETO, SAID RESPIRATORY MEMBER DEFINING A FIRST CHAMBER OPENONLY TO SAID FIRST CONNECTION FOR THE TRAPPING OF THE FIRST PORTION OFTHE EXPIRED BREATH AND THE COLLECTION OF